Apparatus for automatically removing fins of castings

ABSTRACT

An apparatus for automatically removing fins of castings wherein respective air springs are provided to resist a component in the normal direction and a component in the tangential direction with respect to the hone grinding surface of the contact surface of a hone and work of the grinding resistance applied to the grindinghone and are made to be fed with air pressures set in response to the size, thickness and the material of the fin of the work and a motor to control the work in the direction of the component in the normal direction and a motor to control it in the direction of the component in the tangential direction by converting the displacements of the above mentioned air springs to electric signals with two differential transformers are provided.

United States Patent Chunwa et al.

1 APPARATUS FOR AUTOMATICALLY REMOVING FINS OF CASTINGS [75l inventors:Kenji Chijiiwa; Katsun Shirahige,

both of Chiba, Japan I73] Assigncc: Kenji Chijiiwa, Chiba Japan [22]Filed: Sept. 11, 1974 [211 Appl, No: 504,930

[311] Foreign Application Priority Data Sept 17 1973 Japan 48-10467][52] US. Cl 1. 511165.77; 51/161592 [51I Int. Cl .7 B24b 49/16 [SKIField of Search 51/165 R. 165.77, 16592 {56] References Cited UNITEDSTATES PATENTS 3.274.738 9/1966 Kuniholm 51/165 R 3,672,100 6/1972Pesante 51/165]? Aug. s, 1975 I 57] ABSTRACT An apparatus forautomatically removing fins of castings wherein respective air springsare provided to resist a component in the normal direction and a component in the tangential direction with respect to the hone grindingsurface of the contact surface of a hone and work of the grindingresistance applied to the grindinghone and are made to be fed with airpressures set in response to the size, thickness and the material of thetin of the work and a motor to control the work in the direction of thecomponent in the normal direction and a motor to control it in thedirection of the component in the tangential direction by converting thedisplacements of the above mentioned air springs to electric signalswith two differential transformers are provided.

9 Claims, 12 Drawing Figures PATENTEU AUB 51975 (L, van

Lil

PATENTED AUB 51975 SHEET PATENTEI] AUG 5 I975 SHEET PATENTEB 75 SHEETPATENTEUAUB 51975 SHEET mgm w APPARATUS FOR AUTOMATICALLY REMOVING FINSOF CASTINGS This invention relates to an apparatus for automaticallyremoving tins of castings.

The common defects of the conventional sequence, pin board, profilecontrol, numerical value control and tracing memory systems are asfollows:

I. As there is no compensation for the variation of the dimension of theoutside diameter of the grinding hone by its wear, the fin will be leftunrcmoved by the wear of the hone.

2. As the variation of the cutting property with the clogging andcollapsing of the meshes of the hone can not be coped with, the removedamount of the fin will vary. Particularly, if the grinding is automated, self-dressing will be made, therefore the state of the cuttingblade of the hone will vary and the ground amount will come to bedifferent.

3. As there is no protective mechanism, when an extraordinary force isapplied to the hone, there will be a danger.

In the template in the profiling system, the memory tape in the tracingsystem and the instruction tape in the numerical value control, unlessthe fin removing operation starts at the start setting point for thework and the working is made at the same speed, the work and tape willdeviate from each other, a large grinding resistance will be applied tothe hone and the hone and work will be likely to break.

4. The grinding speed can not be adjusted in response to the material,size and thickness of the fin. The desire to make the grinding speedhigh in the part having no tin and to make it low in the part where thefin is hard and thick can not be satisfied.

5. The grinding part is constantly repeatedly moved in the position butdoes not stop in a fixed position due to the inertia. The stoppingposition is related with the characteristics of the motor, the weight ofthe grinding part and the precision and friction of the sliding part ofthe apparatus and there is no function of absorbing the inertia for thevariation of the cutting speed. Therefore, an impact force will belikely to be applied to the work and hone.

An object of the present invention is to provide an apparatus forautomatically removing fins of castings wherein the above mentioneddefects of the conventional fin grinding are eliminated.

FIG. 1 is an explanatory view of the state of contact of a hone and workwith each other.

FIG. 2 is an elevation of an embodiment of the present invention.

FIG. 3 is a plan view of FIG. 2.

FIG. 4 is a partly sectioned elevation of a hone shaft unit.

FlGv 5 is an explanatory view of the controlling relation of the honeand work.

FIGS. 6u-d are explanatory views of the positions of the hone. work andthe core of a differential transformer C.

H65. 711 and h are views showing the relation of the positions ofdifferential transformer and core.

FIG. 8 is a block diagram showing the controlling relations of thedifferential transformers C and D and mo tors M, and M In the presentinvention, a grinding hone is supported with air springs so that the tipof the grinding hone in contact with a work may act as a feeler fordetecting fins with a component Fn in the normal direction and acomponent Ft in the tangential direction with respect to the honegrinding surface as shown in FIG. 1 and the displacements of the airsprings produced by the fluctuation of the grinding resistance may beconverted to electric signals by differential transformers to controlthe displacements of the work or hone and to automatically remove finsof castings.

ln FIGS. 2 and 3, l is a rotary hone set on a supporting stand 16, M isa motor for driving the hone through a belt and set on a supportingstand 2.

W is a work. 3 is a fin to be ground. 4 and 5 are sup porting stands.The work on the supporting stand 4 is rotated by a motor M set on thestand 5.

7 is a base of the present apparatus. A supporting stand 6 is movedthrough a screw rod 8 in the direction of the X axis by a motor Mprovided on the base 7.

A motor M is provided on the supporting stand 6. The supporting stand 5is moved by a screw rod 9 in the direction of the Y axis.

A supporting stand 30 is provided through a rotary shaft 42 on asupporting stand 10 on the base 7. A supporting pillar ll is provided onthe supporting stand 30. A supporting plate 13 is made movable up anddown by a motor M through a screw rod 12 in the direction of the Z axis.

[4 is a nut fitted to the above mentioned screw rod 12 and fixed on oneend surface to the above mentioned supporting plate 13.

The supporting stand 2 is at right angles to the supporting plate 13.The supporting stand 2 and 16 are connected with each other by means ofa pin 17 through a supporting frame 15 of the supporting stand 2.

Air springs (bellows) A and A and a differential transformer C areprovided between the above mentioned supporting stands 2 and 16.

The air spring A is fed with an air pressure Pn preset by the laterdescribed method but will be displaced by the force in the direction ofthe component Fn of the hone and the displacement will be detected bythe differential transformer C.

The air spring A is also fed with an air pressure P'n (Pn 3 P'n) tostabilize the displacement of the supporting stand 2.

A hone shaft unit shall be explained in the following with reference toFIG. 4.

Its main component parts are a hone to grind fins of works, its rotaryshaft 32, a pulley 31 provided at one end of the rotary shaft 32 to hangbelts, a differential transformer D to detect anaxial displacement ofthe hone by the component Fl applied in the axial direction of the hone,air springs B and B to resist the component Ft, pressure receivingplates 18 and 19, bearings 20 and 21, stroke bearings 22 and 23 and ahone shaft barrel 24.

The hone rotary shaft 32 is rotatably supported in both shoulder partswith bearings 20 and 21 which are also supported respectively with thepressure receiving plates 18 and 19 which can slide within the honebarrel 24 so that the hone shaft 32 may be displaced in the axialdirection while rotating.

The air springs B and B are provided respectively between the pressurereeeiving plates 18 and 19 and the 3 end walls 33 and 34 of the honeshaft barrel 24. The internal pressure Pt and P't of the air springs arefed from a compressed air source respectively through pressure reducingvalves. passages 25 and 26 in the walls 33 and 34 and annular paths 3Sand 36.

The above mentioned internal pressures Pt and P! are set by the laterdescribed method.

In order to detect the displacement of the air spring B. that is thedisplacement of the hone shaft 32 with re spect to the hone shaft barrel24, an L-shaped lever 27 is provided to project out of one end of theouter peripheral side of the pressure receiving plate I8 and to come outof the hone shaft barrel 24 through a cut groove 28 of the hone shaftbarrel 24.

The end part of the lever 27 is in contact with the tip of a shaft 39 ofa core 37 of the differential transformer D fixed to the outside of thehone shaft barrel 24 through a pressing force of a spring 38.

By the way. the above mentioned air spring 8 is to stabilize thedisplacement of the hone shaft.

The operation of the grinding hone to remove fins of castings in thepresent invention shall be explained in the following.

First of all. the setting of air pressures of the air springs A, A. Band B shall be explained.

In setting air pressure of the air spring A, the fin of the casting ismade to approach the hone without rotating the casting (the movement ofthe work in the direction of the X axis by the motor M is controlled), apart of the fin is experimentally ground while producing a component Fnand. just when the grinding ends (in the state of (C) in FIG. 6), therequired air pressure Pn of the air spring may be determined.

For this, if the handle ofa cock of the pressure rcducing valve isproperly rotated, the required pressure Pn will be able to bedetermined.

At this time, the following formula will hold. (Sec FIG. 5.)

FM X L =1 X Pn The position of the core of the differential transformerC at this time is so set as to be in the neutral position. (Sec (C) inFIG. 6.) This air pressure Pn is a force pressing the work against thehone required to grind the maximum width part of the bottom part of thefin.

Next. in setting the air pressure Pt of the air spring B. in the stateof (C) in FIG. 6 of the above mentioned experimental grinding, the workW is rotated to produce a force Ft.

The Ft at this time will be of the maximum value as of Ft. Therefore,the air pressure P! which can resist it may be set by rotating the cockof the pressure reducing valve.

If the air pressure Pn and Pt of the air springs A and B are thus set.the pressures P'n and P! of the air springs A and B may be so set as tobe Pn Z P'n and Pt 5. P! by rotating another cock of the pressurereducing valve.

The relation between the relative positions of the work W and hone I inthe direction of the X axis and the differential transformer C shall beexplained in the following. [Sec FIGS. 3, 5, 6 and 7 (41).]

First of all. it is so designed that. when the work W and hone l are notin contact with each other as shown in (a) in FIG. 6. Fri =0 and a core41 of the differential transformer C may be displaced upward by theforce of a spring 40 as illustrated.

The voltage generated by the differential transformer C in this casewill be positive. In FIG. 7, 10 shows the position of the core and itsgenerated voltage is shown by V0.

When the tin 3 of the work begins to contact the hone I, a component Fnwill be generated and the core 41 will be pushed more or less to be inthe state of (b) in FIG. 6. I

In this state. the fin is ground by the operation of the circuit of thelater described apparatus of the present invention.

In (a) in FIG. 7, ll toll show the positions of the core 4] and thevoltages generated by the differential transformer C are V to V When thegrinding of the fin ends. the state of (C) in FIG. 6 will be made. Theposition of the core 41 at this time will be substantially in theneutral position of the differential transformer C and its generatedvoltages will be V to V When the grinding is further continued, thecomponent Fn will quickly become so large that the core 4] will move inthe direction reverse to the above mentioned neutral position and thegenerated voltage will be less than minus V. (d) in FIG. 6 shows thisstate.

Further. in FIG. 7, while the position of the core 4] is I to l by thelater described Schmidt circuit. its out put voltage will be zero and anonsensitive zone will be formed.

The above explanation is summarized as in the following table withreference to FIG. 6.

By the way. in this table, the differential transformer is C and themotor M rotates with the output of the later described Schmidt circuitto control the linear movement in the direction of the X axis of thework.

Table for explaining FIG. (1

The control of the rotation of the work by the motor M is made in therelation of the component F air spring B and differential transformer D.

In this case, as different from the case of the above described controlof the linear movement of the work, when Ft is 0 or of a small valueclose to O, that is, in the state of (a), (h) or (c) in FIG. 6, the coreof the differential transformer D will be in the neutral position andthe motor M, will not rotate. At the end of the state of (C), by itssignal, the motor M will rotate at a low speed. When F! is of acorresponding value by the contact with the fin, the grinding will becontinued.

The operation of the present apparatus shall be explained in thefollowing with reference to FIG. 8. First of all, the main steps of theautomatic grinding of fins with the present apparatus shall beenumerated.

First step: The motor M to feed the work with respect to the honenormally rotates at a high speed.

Second step: The grinding of the fin in the part in contact with thehone while Fn is being produced begins but the work does not rotate.

Third step: The grinding of the fin in the above mentioned contact partends. (The state of (C) in FIG. 6.)

Fourth step: The rotation of the work begins.

Fifth step: When a new fin is contacted by the rotation of the work, asF! is larger than the corresponding value, the grinding of the fin willbe continued.

Sixth step: When the hone enters the dead angle of the work, F! willbecome infinite. In this case. the motor M will reversely rotate at alow speed and the motor M will stop.

Seventh step: The grinding of the fin ends and the motor M reverselyrotates at a low speed to return to the original fixed position.

The above steps shall be explained with reference to the block diagramin FIG. 8.

In the first step, as the differential transformer C is in the state of(a) in FIG. 6, the electromotivc voltage of the differential transformerC will be an input in the Schmidt circuit S. and, by its output, themotor M, will be normally rotated at a high speed through a relay R tomake the work of the first step.

In the second step, as the differential transformer C is in the state of(b) in FIG. 6, due to the value of the electromotive voltage of thedifferential transformer C, by the Schmidt circuit 5,, the relay R willbe switched over to a current source for low speeds and the motor M willnormally rotate at a low speed and the fin grinding in the third stepwill be also made.

In and after the fourth step, any of the following five steps is made.

4 I: In the case there is no fin:

By the input electric power V of the Schmidt circuit, the current sourceof the motor M will be cut by the relay R through the Schmidt circuitand at the same time the relay R will be operated to switch on thecurrent source of the motor M that is to say, the work will begin torotate.

At this time, as there is no fin, the differential transformer I) willbe in the state of V... [See (h) in FIG. 7| the Schmidt circuit will bein the state of S and the relay R will be normally rotating the motor Mat a high speed.

4 2: In case a fin is present:

The motor M will remain stopped, the electromotive force from thedifferential transformer D will become V, and, by the relay R the motorM, will be switched over to the normal rotation at a low speed to grindthe fin.

4 3: In case the hone enters the dead angle of the work:

The electromotive force of the differential transformer D will be in thestate of V the Schmidt circuit S will operate the relay R the motor M,will be reversly rotated and the motor M, will be stopped.

4 4: In case the hone bites into the work:

The electromotive force of the differential transformer C will be in thestate of V the relay R will be operated by the Schmidt circuit S themotor M will reversely rotate and the work will retreat.

4 5: In case the work makes one rotation:

When the work makes one rotation, the current source of the motor M,will be cut by the relay R the rotation of the work will stop and themotor M will reversely rotate to return the work to the originalposition.

By the way, when the work is a rectangle long in the direction of the Yaxis, the displacement of the work may be controlled with the motor M.The control of the motor M is exactly the same as the control of therotation of the motor M and the current source may be switched over soas to control the motor M instead of the motor M Further, in FIG. 2, arotary shaft 42 is provided between the supporting stands 10 and 30 soas to be used on manually setting the position of the hone with respectto the work.

The present invention is of such formation as is described above,therefore has an effect of eliminating various defects of theconventional grinding of fins and is summarized as follows:

I. It has a mechanism wherein, when the fin contacts the tip of thehone, the bone will escape in response to the thickness, size andhardness of the fin.

Further, when the hone removes the fin and reaches the body of the work,the advance of the work will stop. When the work receives a force fromthe hone, the work will retreat. That is to say, as the tip of the honeacts as a feeler of a fin detector, even if the outside diameter of thehone varies, the tip of the bone will be always in contact with the rootof the fin.

2. The matrix of the profiling system, program of the numerical valuecontrol and magnetic tape tracing memory are not required.

3. Irrespective of the chucking posture, the starting point of theworking can be freely selected anywhere.

4. The inertia force of the grinding head caused by the high speed ofthe working can be adjusted by adjusting the pressure of the air spring.

As in the above, in the present invention, the operation of removingfins of castings can be reasonably and simply automated.

We claim:

I. An apparatus for automatically removing fins of castingscharacterized by comprising a first air spring means for resisting acomponent in the normal direction with respect to the hone grindingsurface of the contact surface of a hone and work of the grindingresistance applied to the grinding hone, a second air spring means forresisting a component in the tangential direction, a means of feedingsaid two air spring means with desired air pressure set in response tothe fin of the work, a first differential transformer for converting thedisplacement of said first air spring means to an electric signal, asecond differential transformer for converting the displacement of saidsecond air spring to an electric signal, a first motor means forcontrolling said work in the direction of said component in the normaldirection and a second motor means for controlling said work in thedirection of said component in the tangential direction.

2. An apparatus for automatically removing fins of castings according toclaim 1 characterized in that said first air spring means is providedbetween two parallel supporting stands which are connected with eachother by means ofa pin through a supporting frame of one of thesupporting stands.

3. An apparatus for automatically removing fins of castings according toclaim 1 characterized in that a hone shaft unit includes said second airspring means and second differential transformer.

4. An apparatus for automatically removing fins of castings according toclaim 3 characterized in that said hone shaft unit further includes ahone rotary shaft, a pulley provided at one end of said rotary shaft tohang belts, a pair of pressure receiving plates, a pair of bearings, apair of stroke bearings provided on the outer periphery of said shaftand a hone shaft barrel containing these members.

5. An apparatus for automatically removing fins of castings according toclaim 2 characterized in that the air pressure of said first air springmeans is set by the formula wherein Fn is a component in the normaldirection with respect to the hone grinding surface of the contactsurface of the hone and work Pn is a component in the tangentialdirection, 1 is a distance between the pin and air spring means and L isa distance between the pin and the contact point of the fin and hone.

6. An apparatus for automatically removing fins of castings according toclaim 2 characterized in that the air pressure of said second air springmeans is set by rotating a pressure reducing valve so as to feed an airpressure corresponding to said component in the tangential directionjust when the grinding ends.

7. An apparatus for automatically removing fins of castings according toclaim 1 characterized in that said first differential transformerconsists of a core and spring. the core is deviated upward by the springand the generated voltage in this state is positive.

8. An apparatus for automatically removing fins of castings according tocalim 1 characterized in that said means of feeding the first air springmeans with an air pressure comprises a compressed air source, a pressurereducing valve and paths.

9. An apparatus for automatically removing fins of castings according toclaim l characterized in that said means of feeding the second airspring means with an air pressure comprises a compressed air source. apressure reducing valve, paths in both end walls of the shaft barrel andannular paths.

1. An apparatus for automatically removing fins of castingscharacterized by comprising a first air spring means for resisting acomponent in the normal direction with respect to the hone grindingsurface of the contact surface of a hone and work of the grindingresistance applied to the grinding hone, a second air spring means forresisting a component in the tangential direction, a means of feedingsaid two air spring means with desired air pressure set in response tothe fin of the work, a first differential transformer for converting thedisplacement of said first air spring means to an electric signal, asecond differential transformer for converting the displacement of saidsecond air spring to an electric signal, a first motor means forcontrolling said work in the direction of said component in the normaldirection and a second motor means for controlling said work in thedirection of said component in the tangential direction.
 2. An apparatusfor automatically removing fins of castings according to claim 1characterized in that said first air spring means is provided betweentwo parallel supporting stands which are connected with each other bymeans of a pin through a supporting frame of one of the supportingstands.
 3. An apparatus for automatically removing fins of castingsaccording to claim 1 characterized in that a hone shaft unit includessaid second air spring means and second differential transformer.
 4. Anapparatus for automatically removing fins of castings according to claim3 characterized in that said hone shaft unit further includes a honerotary shaft, a pulley provided at one end of said rotary shaft to hangbelts, a pair of pressure receiving plates, a pair of bearings, a pairof stroke bearings provided on the outer periphery of said shaft and ahone shaft barrel containing these members.
 5. An apparatus forautomatically removing fins of castings according to claim 2characterized in that the air pressure of said first air spring means isset by the formula Fn X L l X Pn wherein Fn is a component in the normaldirection with respect to the hone grinding surface of the contactsurface of the hone and work, Pn is a component in the tangentialdirection, l is a distance between the pin and air spring means and L isa distance between the pin and the contact point of the fin and hone. 6.An apparatus for automatically removing fins of castings according toclaim 2 characterized in that the air pressure of said second air springmeans is set by rotating a pressure reducing valve so as to feed an airpressure corresponding to said component in the tangential directionjust when the grinding ends.
 7. An apparatus for automatically removingfins of castings according to claim 1 characterized in that said firstdifferential transformer consists of a core and spring, the core isdeviated upward by the spring and the generated voltage in this state ispositive.
 8. An apparatus for automatically removing fins of castingsaccording to calim 1 characterized in that said means of feeding thefirst air spring means with an air pressure comprises a compressed airsource, a pressure reducing valve and paths.
 9. An apparatus forautomatically removing fins of castings according to claim 1characterized in that said means Of feeding the second air spring meanswith an air pressure comprises a compressed air source, a pressurereducing valve, paths in both end walls of the shaft barrel and annularpaths.